Get your semi Ready for the Road Ahead™ with a quiet belt that generates stable electricity, with the Dayco 1.66" x 47.72" Poly Rib® Heavy Duty Serpentine Belt. This replacement belt works with multiple tight pulleys and the alternator to convert the mechanical energy of the engine into electrical power for accessories. Engineered with modern EDPM rubber materials to reduce how often a belt should be changed. FleetPride is your First Click in Heavy Duty®.